Self-winding wrist-watch



Feb. 9, 1932. A BULOVA 1,844,882

SELF WINDING WRIST WATCH Filed Jan. 4, 1950 Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE ABDE BULOVA, NEW YORK, N. Y ASSIGNOJ, TO BULOVA WATCH COMPANY, INC

' 4 01 NEW YORK, N. Y A CORPORATION OF NEW YORK SELF-WINDING WRIST-WATCH This invention relates to' self-winding watches and particularly to self-winding wrist-watches.

In these watches the windin pawl and ratchet. The smallness of the watch and the shortness of the arm on which the weight can be swun make it important that the weight be very rec in its movement. The shortness of the arm requires that the weight be relatively heavy, and in order to accommodate such a weight without increasing the thickness of the watch so that it would be unacceptable, the weight is located outside the periphery of the movement, this location also giving a greater length of armthan would be possible if the weight operated over one face ofthe movement.

In order to insurethe desired freedom of o movement of the weight, it has been the practice to swing it from two alined pivots by means of two arms extending over opposite faces of the movement. These arms are free of the movement, and by reason of the depth of the spacing between their pivots, serve to keep, the weight in position as against movement up or down. A serious disadvantage of this construction is that it makes it-impossible to use a second hand on the watch.

In the present invention the weight 1s swung on a single arm, which makes possible a reduction in thickness of the watch, and the Weight is guidedbetween upper and lower rings or plates forming tracks, these rings being inside or part of the case but outside the movement, constituting covers for the peripheral recess in which the weight operates. The desired freedom of movement is secured by forming cavities in the opposite sides of the weight, in which cavities there are balls adapted to cooperate with the two tracks in a manner to reduce frictional resistance to a minimum. At each side of the weight, the cavities and the balls are located at points spaced at opposite sides of the center of length of the weight, or near its ends, so as to preclude any possibility of the weight itself tilting and dragging on one track or the other.

train is ac- 5' tuated by an oscillatory weig t through a Reference will be made t6 the accompanying drawings forming part hereof.

ig. 1 is a rear view of the movementand a part enclrchng the movement of a watch embodying the features of my invention. The watch movement is represented sufficiently for an understanding of the invention.

Fig. 2 1s a cross-section on a lar er scale, taken onthe line 2'2 of Fig. 1, t e movement being prlncipally'in elevation without a showln 0 its familiar details. For clearness of 1 lustration the distances at which parts are spaced for clearance are exaggerated.

Fig. 3 is a much enlar ed section throu h the winding ratchet wh e and one pa'rtof t e friction connection in a :ondition prior to assembling.

Fi 4'is a section throu h the pinion forming t e other part of the riction safety connection. v

5 is a section of these parts assembled.

Fig. 6 is a fragmentary face view looking at the under side of Fig. 3.

Figs. 7 and 8 are views lookin at opposite sides of the weight and weig t arm.

The movement as a whole is designated 2, and 3 is a part into which the movement is set. This part may be regarded as bein part of the case, or it may be a filler piece w ich conforms to the interior of the case proper. The construction is such that a recess 4 is formed in the part 3, that is to sa inside the case and around the movement. ne portion of this recess is occupied by a fixed block 5, which could be integral with the part 3.

A brid e 6 secured to the block 5 extends over the back of the movement, and its depressed extremity carries a hollow. pivot 7 the axis of which is in line with the center of the movement.

A ratchet wheel 8, having a hub 9, is placed is secured at. its outer end to an arc-shaped weight 14 which lies in the recess 4. On

the inner side of the weight arm there is a pawl 15 pressed by a spring 16 to engage the ratchet wheel 8.

, The weight-arm 13 and the ratchet wheel 8' with its pinion are retained about the pivot 7 by means of a headed screw 17 engaging threads on the inside of the hollow -10 pivot.

On the upper and also on the lower side, the weight has small cavities 18 holding balls 19 which protrude slightly beyond the surfaces of the weight. As clearly shown in Figs. 7 and 8 there are preferably at least two of these balls on each side of the weight,

. spaced apart at opposite sides of the center of length of the we1 ht.

The purpose of t ese balls is to contact flo'rollingly with upper andlower track members 20 and'21 at top and bottom of the remass 4. These track members consist pref-.

erably of flat rings, which are secured to the block 5 and which may be secured elsewhere 26 to the movement and to the part 3, as desired.

By reason of this construction the weight is reliably guided with only a single arm to connect it with the center pivot, and fric- 'tional resistance tending to restrain the 30 movement of the weight is kept as low as possible, since the weight itself can not come 1n contact with the two tracks.

7 Figs. .3 to 6 illustrate a safety connectlon which is introduced into the winding mechanismto avoid injury which would result if over-winding were not prevented. The wheel 8 is shown provided with a collar pro ecting from one face, the circuit of this collar being interrupted by slots 22 'of greater or less 40 width forming free sections or fingers 23,

v which possess a substantial degree of resilience or elasticity. These fingers may be so formed that normally the flare or iverge, though that is not essentia In the construc- '45 tion illustrated, however, they must be crowded or compressed inward in order to be received bythe large central opening'24 of the pinion 10, with the result that the fingers press outward against the, encircling wall of this openin thereby firmly connecting the parts toget er for the transmission 0 the winding im ulses due tothe movement of the weight, ut insuring slippage when the stress becomes greatert an a predetermined safe amount which is reached when the mainsprin is wound as much as it should be. I find t at a safety oonnection'of this type is highly reliable, that it is easy to establish 7 the proper amount of resilient pressure and friction in the first instance-and that the ac tion'will remain substantially constant over a long period of use. The sections or fingers 23 preserve their elasticity unchaii ed indefinitely, there is little opportunit or dirt 6 to enter between the frictional sur aces, and

adjusting screws or the like are not required.

I am aware of the Brun Patent 271,030, dated J anuary 23, 1883, which shows a winding weight swung by a single arm, the extremity of which carries a frictional roll which travels between andagainst a plate of the movement and a raised rail or bar" secured to this plate. The construction disclosed inithe patent is one which could not be employed in asmall wrist-watch, and the roll is ill-adapted for reducing friction. Furthermore, the roller located at the extremity of the arm does not prevent the weight from tipping and dragging onthe plate. I do not necessarily exclude the use of rollers in my invention, provided they are properly disposed, but balls held in cavities in the weight ave numerous advantages in respect to simplicity, greater efficiency in reducing friction, and the fact that the weight need be cut awa but very little.

It will be un erstood that I do not limit myself to the precise form and details of the construction illustrated herein, since these may be varied without departing from the .scope of the invention set forth in the appended claims.

I claim: I

1. In a self-winding watch having a winding train, a movement, a case having a recess outside the periphery of the movement, a weight oscillatory'in said recess to operate the winding train, a single arm extending over one face of the movement to swing said weight from a center, track members at top and bottom of the peripheral recess, said weight being formed with cavities in itsopposite sides, and balls protruding from said cavities to cooperate with said track members. i i

2. In a self-winding watch having a winding train, an oscillatory weight and means whereby the movements of said weight operate the winding train, a single pivoted arm by which said weight is swung from a center, upper and lower tracks between which said weight oscillates, and anti-friction devices carried. by said weight at opposite sides of the center of length of the weight to cooperate with said tracks, there being two sets of said devices cooperating, respectively, with the upper and with the lower track.

i ARDE BULOVA. 

